I've been going to linux.conf.au for 18 years now (since 2001), and presented a fair amount of linux talks related there, but the big change for me was the open hardware miniconf that started in 2010. Thanks to its projects every year, I got to learn a lot about microcontrollers and some about electronics.
This talk was my first non linux talk which detailled everything I learned from those miniconfs and projects I worked that stemmed from them. I presented it at LCA 2019 Christchurch.

After finishing the code tuning and demos just in time, gave a 20mn miniconf talk on the history of linux.conf.au hardware miniconf. I went through how much I learned from those confs and what I was able to achieve as a result. I sure got to learn a lot about microcontroller and driver programming:

I wasn't able to bring my burning man 4096 neopixel matrix, it doesn't even fit in my car, but the irony is that my small 64x64 rgbpanel has the same resolution and fits easily in my backpack

The 64x64 compact display is showing the hand X-ray here

A few days later, I gave the longer version of my talk at the main conference. By then it had grown to over 160 slides in a 45mn slot, or 16 seconds per slide. Ooops...

The full talk went into details on what I learned in the hardware hacking field, a lot of it was simply electricity, U=RI, wires, pre-made components (small inline volt/amp meters, DC-DC converters, and so forth).